update `strata` var to `group_var` #3121

Job	Run time
Version Bump 🤜🤛	0s
Audit Dependencies 🕵️‍♂️ / oysteR scan 🦪	1m 32s
R CMD Check (non-CRAN) 🧬 / ghcr.io/insightsengineering/rstudio, version latest	11m 7s
Coverage 📔 / Coverage 📔	10m 9s
Coverage 📔 / Covtracer 🐄	0s
Roxygen 🅾 / Manual pages check 🏁	8m 42s
R CMD Check 🧬 / ghcr.io/insightsengineering/rstudio, version latest	25m 51s
SuperLinter 🦸‍♀️ / SuperLinter 🦸‍♂️	1m 28s
SuperLinter 🦸‍♀️ / Lint R code 🧶	1m 34s
gitleaks 💧 / gitleaks 💧	3s
gitleaks 💧 / PII Check 💳	0s
License Check 🃏 / Check 🚩	35s
Check URLs 🌐 / Validate Links 🔎	0s
Check URLs 🌐 / URL Checker 🔎	46s
Version Check 🏁 / Emoji in NEWS.md 📰	11s
Spell Check 🆎 / Check spelling 🔠	1m 37s
Version Check 🏁 / Version check 🏁	3s
Grammar Check 🔤 / Check 📝	13s
Style Check 👗 / Check code style 🔠	1m 45s
Coverage 📔 / Publish coverage report 📰	0s
R CMD Check (non-CRAN) 🧬 / Publish JUnit HTML report 📰	0s
R CMD Check (non-CRAN) 🧬 / Upload build tar.gz	0s
R CMD Check 🧬 / Upload build tar.gz	1s
R CMD Check 🧬 / Publish JUnit HTML report 📰	1s
	1h 5m 38s

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